In previous studies we demonstrated that angiotensin II (Ang II) increases macrophage migration inhibitory factor (MIF) levels within hypothalamic neurons in culture, and that MIF acts intracellularly to inhibit the neuronal chronotropic actions of Ang II. Further, this inhibitory effect was mediated via the thiol protein oxidoreductase activity (TPOR) of the MIF molecule. Here we have examined whether similar Ang II/MIF interactions occur in the CNS in vivo, and whether MIF serves to inhibit the CNS-mediated actions of Ang II on blood pressure and water intake. Intracerebroventricular (icv) injection of Ang II (10 pmol) into normotensive rats increased MIF levels in the paraventricular nucleus (PVN), a site that is important in regulating sympathetic outflow and the CNS actions of Ang II. Viral-mediated (Ad-Syn-MIF) over expression of MIF within PVN neurons blunted the pressor and dipsogenic actions of icv-injected Ang II, when compared with Ad-Syn-GFP-treated or control animals. Intracellular application of MIF into PVN sympathetic regulatory neurons (contained within hypothalamic slices) blunted the stimulatory actions of Ang II on PVN neuronal discharge. A similar inhibitory effect was obtained with MIF-(50–65), a peptide that harbors the TPOR activity of MIF. These data provide the first evidence that MIF can regulate the CNS actions of Ang II, mediated via the PVN, on blood pressure and water intake, and suggest the involvement of a TPOR-mechanism in this response.